package com.hmdp.service.impl;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.RedisConstants;
import com.hmdp.utils.RedisData;
import com.hmdp.utils.SystemConstants;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.geo.Circle;
import org.springframework.data.geo.Distance;
import org.springframework.data.geo.GeoResult;
import org.springframework.data.geo.GeoResults;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.domain.geo.GeoReference;
import org.springframework.data.redis.domain.geo.Metrics;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import java.time.LocalDateTime;
import java.util.*;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {
    @Autowired
    private StringRedisTemplate stringRedisTemplate;
    @Override
    public Result queryById(Long id) {
        //缓存穿透
        Shop shop = queryWithPassThough(id);

        //互斥锁解决缓存击穿问题
        //Shop shop = queryWithMutex(id);
        //用逻辑过期解决缓存击穿问题
        //Shop shop = queryWithLogicalExpire(id);
        if(shop == null){
            return Result.fail("商户不存在");
        }
        return Result.ok(shop);
    }
    //互斥锁解决缓存击穿问题
    public Shop queryWithMutex(Long id){
        //1.从redis中查询商户缓存
        String shopJson = stringRedisTemplate.opsForValue().get("cache:shop:" + id);
        //2.判断商户是否存在
        //如果命中直接返回结果
        if(StrUtil.isNotBlank(shopJson)){
            Shop shop = JSONUtil.toBean(shopJson, Shop.class);
            //3.存在，直接返回
            return shop;
        }
        //判断命中是否是空值
        if(shopJson != null){
            //这个分支其实就是shopJson =="",其实就是返回缓存穿透的结果
            return null;
        }
        //4.实现缓存重建
        //4.1获取互斥锁
        Shop shop = null;
        String lockKey = RedisConstants.LOCK_SHOP_KEY + id;
        try {
            boolean isLock = tryLock(lockKey);
            //4.2判断是否获取锁成功
            if(!isLock){
                //4.3如果失败则休眠并重试
                Thread.sleep(50);
                return queryWithMutex(id);
            }
            //4.4成功，从数据库查询
            shop = getById(id);
            //模拟重建延迟
            Thread.sleep(200);
            //5.不存在，返回错误
            if(shop == null){
                //解决缓存穿透问题
                //将空值写入redis并设置过期时间
                stringRedisTemplate.opsForValue().set("cache:shop:" + id,"", RedisConstants.CACHE_NULL_TTL,
                        TimeUnit.MINUTES);
                return null;
            }
            //6.存在将商户信息写入redis
            stringRedisTemplate.opsForValue().set("cache:shop:" + id,JSONUtil.toJsonStr(shop));
            //释放互斥锁
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }finally {
            unLock(lockKey);
        }
        //7.返回
        return shop;
    }
    //解决缓存穿透
    public Shop queryWithPassThough(Long id){
        //1.从redis中查询商户缓存
        String shopJson = stringRedisTemplate.opsForValue().get("cache:shop:" + id);
        //2.判断商户是否存在
        if(StrUtil.isNotBlank(shopJson)){
            Shop shop = JSONUtil.toBean(shopJson, Shop.class);
            //3.存在，直接返回
            return shop;
        }
        //判断命中是否是空值
        if(shopJson != null){
            return null;
        }
        //4.不存在，从数据库查询
        Shop shop = getById(id);
        //5.不存在，返回错误
        if(shop == null){
            //解决缓存穿透问题
            //将空值写入redis并设置过期时间
            stringRedisTemplate.opsForValue().set("cache:shop:" + id,"", RedisConstants.CACHE_NULL_TTL,
                    TimeUnit.MINUTES);
            return null;
        }
        //6.存在将商户信息写入redis
        stringRedisTemplate.opsForValue().set("cache:shop:" + id,JSONUtil.toJsonStr(shop));
        //7.返回
        return shop;
    }

    //获取锁
    private boolean tryLock(String key){
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }
    //释放锁
    private void unLock(String key){
        stringRedisTemplate.delete(key);
    }

    @Override
    @Transactional
    public Result update(Shop shop) {
        if(shop.getId() == null){
            return Result.fail("商户id不能为空");
        }
        //1.更新数据库
        updateById(shop);
        //2.删除缓存
        stringRedisTemplate.delete("cache:shop:" + shop.getId());
        return Result.ok();
    }


    public void saveShop2Redis(Long id,Long expireSeconds) throws InterruptedException {
        //1.查询店铺数据
        Shop shop = getById(id);
        Thread.sleep(200);
        //2.封装逻辑过期时间
        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
        //3.写入redis
        stringRedisTemplate.opsForValue().set("cache:shop:" + id,JSONUtil.toJsonStr(redisData));
    }

    public Shop queryWithLogicalExpire(Long id){
        //1.从redis中查询商户缓存
        String shopJson = stringRedisTemplate.opsForValue().get("cache:shop:" + id);
        //2.判断商户是否存在
        if(StrUtil.isBlank(shopJson)){
            //如果不存在
            return null;
        }
        //4.命中，需要先把json反序列化为对象
        RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
        //5.判断是否过期
        LocalDateTime expireTime = redisData.getExpireTime();
        Object data = redisData.getData();
        JSONObject jsonObject = JSONUtil.parseObj(data);
        Shop shop = JSONUtil.toBean(jsonObject, Shop.class);

        if(expireTime.isAfter(LocalDateTime.now())){
            //5.1未过期直接返回店铺信息
            return shop;
        }
        //5.2已过期，需要缓存重建
        //6.缓存重建
        String lockKey = RedisConstants.LOCK_SHOP_KEY + id;
        //6.1 获取互斥锁
        boolean isLock = tryLock(lockKey);
        //6.2 判断是否获取成功
        if(isLock){
            //6.3 成功，开启一个独立线程实现缓存重建
            CACHE_REBUILD_EXECUTOR.submit(()->{
                //重建缓存
                try {
                    this.saveShop2Redis(id,30L);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                } finally {
                    //释放锁
                    unLock(lockKey);
                }
            });
        }
        //6.4无论失败与否都会返回过期的商铺信息
        return shop;
    }
    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);

    @Override
    public Result queryShopByType(Integer typeId, Integer current, Double x, Double y) {
        //1.判断是否需要根据坐标查询
        if(x == null || y == null){
            //不需要坐标查询
            Page<Shop> page = query()
                    .eq("type_id", typeId)
                    //current表示当前分页的页码
                    .page(new Page<>(current, SystemConstants.DEFAULT_PAGE_SIZE));
            //5.返回
            return Result.ok(page.getRecords());
        }
        //2.计算分页参数
        //计算页码，也就是开始页和结束页
        int from = (current - 1) * SystemConstants.DEFAULT_PAGE_SIZE;
        int end = current * SystemConstants.DEFAULT_PAGE_SIZE;
        //3.查询Redis、按照距离排序、分页 结果：shopId、distance
        String key = RedisConstants.SHOP_GEO_KEY + typeId;
        /*GeoResults<RedisGeoCommands.GeoLocation<String>> results = stringRedisTemplate.opsForGeo().search(
                key,
                GeoReference.fromCoordinate(x, y),
                new Distance(5000),
                RedisGeoCommands.GeoSearchCommandArgs.newGeoSearchArgs().includeDistance()
                        .limit(end)
        );*/
        // 使用 GEORADIUS 命令
        Circle circle = new Circle(x, y, 5000);
        GeoResults<RedisGeoCommands.GeoLocation<String>> results = stringRedisTemplate.opsForGeo().radius(
                key,
                circle,
                RedisGeoCommands.GeoRadiusCommandArgs.newGeoRadiusArgs().includeDistance().limit(end)
        );
        //4.解析出id
        if(results == null){
            return Result.ok(Collections.emptyList());
        }
        List<GeoResult<RedisGeoCommands.GeoLocation<String>>> list = results.getContent();
        //截取from到end的部分
        List<Long> ids = new ArrayList<>(list.size());
        if(list.size()<=from){
            return Result.ok(Collections.emptyList());
        }
        Map<String, Distance> distanceMap = new HashMap<>(list.size());
        list.stream().skip(from).forEach(result -> {
            //获取店铺id
            String shopId = result.getContent().getName();
            ids.add(Long.valueOf(shopId));
            //获取店铺距离
            Distance distance = result.getDistance();
            distanceMap.put(shopId, distance);
        });
        //5.根据id查询Shop
        String idStr = StrUtil.join(",", ids);
        List<Shop> shops = query().in("id", ids).last("ORDER BY FIELD(id," + idStr + ")").list();
        for (Shop shop : shops) {
            shop.setDistance(distanceMap.get(shop.getId().toString()).getValue());
        }
        //6.返回
        return Result.ok(shops);
    }
}
